This invention relates to a method of ventilating an animal enclosure according to the outside ambient temperature. Applicant's U.S. Pat. No. 4,602,739 discloses an Apparatus and Method for Ventilating Animal Enclosures which relies on a variation in fan operation intervals in response to outside air temperature changes to maintain proper ventilation within an animal enclosure. The explanation of the importance of proper ventilation contained in the Patent is incorporated herein. The invention disclosed in this application is a further improvement in controlling ventilation efficiency during relatively wide ranges of outside ambient temperature change.
This invention relates particularly to enclosures used to raise poultry, particularly chickens and turkeys. Modern day poultry houses are usually well insulated and are equipped with some type of ventilation system to minimize heat buildup in the house and to exchange inside air laden with products of animal respiration and waste with fresh, outside air. In the southern United States, the open walled house with adjustable curtains is typical. This type of poultry house is shown in Applicant's U.S. Pat. Nos. 3,915,377, 4,113,175 and 4,602,739.
The use of sidewall curtains permits natural ventilation when temperature conditions permit. In cold weather the curtains can be closed and powered fans used to more carefully control temperature and air exchange rates within the house. This type of ventilation is carried out with sidewall fans spaced along the length of the enclosure. Air is pulled into the house along one side and exhausted on the other side through the ventilation fans. When the outside temperature exceeds 80 degrees, common practice is to remove the fans from the sidewalls and relocate them in the middle of the house. The end doors are opened and the fans are aimed to blow towards one end. Foggers are sometimes used to create a mist of water, thereby causing some evaporative cooling. This is a common method of providing supplemental natural ventilation.
A newer type of ventilation is "tunnel ventilation." This type of ventilation relies on relatively high air velocities within the house and is based on the observed fact that air movement decreases the effective temperature that an animal senses. This is referred to as a "wind-chill" effect and is most often used to adjust downwardly the temperature during very cold weather to take into account the sensation of the wind in combination with the temperature on the skin.
To the extent that movement of air can decrease the effective temperature sensed by an animal, stress upon the animal can reduced below that which would result at the same temperature with no or a lesser velocity of air movement.
Without the use of "tunnel" ventilation, cooling is the greatest near the hanging fans in the middle of the house. The poultry tend to gather in front of the fans and away from the ends of the house. Overcrowding can cause heat and carbon dioxide buildup, thereby negating the desired effect of the fans and the mist.